Field of the Invention
Embodiments of the present invention relate to a controller for an internal combustion engine. More particularly, embodiments of the present invention relate to a controller for an internal combustion engine suitable as an onboard controller for an internal combustion engine that performs a lean burn operation.
Background Art
Japanese Patent Laid-Open No. 2013-124544 (hereafter, referred to as Patent Document 1) discloses an internal combustion engine provided with a positive crankcase ventilation (PCV) valve and an ejector. A blow-by gas containing NOx and CO2 can flow through the crankcase of an internal combustion engine. Thus, an internal combustion engine requires appropriate ventilation of gas in the crankcase (referred to as an “in-case gas”, hereinafter).
The PCV valve is disposed between the crankcase and the intake passage so as to suck the in-case gas into the intake passage by using the negative pressure of the intake air. The PCV valve can appropriately ventilate the interior of the crankcase under a situation where an appropriate negative pressure of the intake air occurs.
The ejector is mounted on the internal combustion engine along with a supercharger. In the internal combustion engine provided with a supercharger, a pressure difference occurs between before and after the compressor. The ejector has an inlet that is in communication with the interior of the crankcase, an outlet that is in communication with a part upstream of the compressor and a pressure introduction port that is in communication with a part downstream of the compressor. With such a configuration, when a pressure difference occurs between before and after the compressor, an air flow from the pressure introduction port to the outlet occurs in the ejector. Once such an air flow occurs, the ejector ejects the in-case gas sucked in through the inlet through the outlet. Thus, the ejector can appropriately ventilate the interior of the crankcase under a situation where an appropriate supercharging pressure occurs.